What Kind Of Gas For Lawn Mower?

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By Kirsi Jansa

Selecting the best gas for lawn mowers is crucial for the optimal performance and longevity of the equipment. Here’s an in-depth analysis to help you make an informed decision.

What Kind Of Gas For Lawn Mower

Best Gas for Lawn Mowers

Octane Rating

Ideal Rating: Lawn mowers typically require gas with an octane rating of 87 or higher.

Reason: Higher octane fuel generally reduces the risk of knocking in the engine, improving performance and efficiency.

Ethanol Content

E10 or Less: Most manufacturers recommend using gasoline with no more than 10% ethanol (E10).

Reason: Higher ethanol content can cause corrosion, deterioration of fuel lines, and damage to the engine and fuel system components.

Fuel Stabilizers

Usage: Adding a fuel stabilizer to the gas is recommended, especially if the gas will be stored in the tank for an extended period.

Reason: Stabilizers prevent fuel from degrading, which can lead to the formation of gums and varnishes that clog the fuel system.

Storage and Freshness

Fresh Fuel: It’s advised to use fresh gas, not older than 30 days.

Reason: Old gas loses volatility, leading to starting problems and reduced performance.

Fuel Storage Container

Approved Containers: Use only containers approved for fuel storage.

Reason: Approved containers are designed to reduce the risk of spillage and contamination.

Non-ethanol Gasoline

Preference: If available, non-ethanol gas can be the best option for small engines.

Reason: Non-ethanol gas reduces the risk of engine corrosion and fuel system damage, especially in equipment that is not used regularly.

Additives and Cleaners

Occasional Use: Consider using additives and fuel system cleaners occasionally.

Reasons: These products can help keep the fuel system clean and remove any deposits, ensuring optimal performance.

Avoidance of Lower Quality Gas

Higher Quality: Opt for higher-quality gas from reputable gas stations.

Reason: Lower quality gas may contain more contaminants and impurities that can clog the fuel system.

Environment Consideration

Alternative Fuels: Consider environmentally friendly alternatives where possible.

Reason: While traditional gasoline is the most common fuel, propane and biodiesel are cleaner-burning alternatives available for certain mowers.

Manufacturer’s Recommendations

Compliance: Always comply with the manufacturer’s recommendations regarding fuel.

Reason: Different lawn mowers might have specific fuel requirements, and adhering to them ensures the longevity and efficiency of the engine

What Kind Of Gas For Lawn Mower

Two-Stroke Engines: Mixing Oil & Gas

Two-stroke engines, unlike four-stroke engines, require a mixture of oil and gasoline for proper lubrication and combustion. The oil in the mix lubricates the engine’s internal components, while the gasoline acts as the fuel.

Mixing Process

Identify Ratio: Determine the appropriate oil-to-gas ratio as specified by the engine manufacturer. Common ratios include 50:1 and 40:1.

Measuring: Measure the correct amount of two-stroke engine oil based on the ratio and the gasoline you will mix.

Mixing: Pour the oil into the gasoline container, then add the gasoline. Seal the container and shake it to ensure a thorough mix.

Ratio for 1 Gallon of Gas

For a 50:1 ratio, you would mix 2.56 ounces of oil to one gallon of gasoline (128 ounces / 50 = 2.56 ounces).

For a 40:1 ratio, you would mix 3.2 ounces of oil to one gallon of gasoline (128 ounces / 40 = 3.2 ounces)

Two-Stroke Engines Mixing Oil & Gas

Four-Stroke Engines: Which gas is Best?

It is generally best to use fresh, unleaded gasoline with an octane rating of 87 or higher for four-stroke engines. Avoiding fuel with high ethanol content (above 10%) is advisable as it can cause damage over time. Additionally, adhering to the specific fuel recommendations provided in the engine’s manual ensures optimal performance and longevity.

Four-Stroke Engine

Ethanol-Free Gas for Lawn Mowers

Ethanol-free gas is a type of fuel that does not contain ethanol, making it suitable for lawn mowers, especially those used intermittently, as it prevents certain types of damage associated with ethanol.


  • Performance: Offers better performance with more consistent combustion, enhancing the efficiency of lawn mowers.
  • Longevity: Prevents corrosion and degradation of fuel system components, extending the life of the equipment.
  • Fuel Stability: Ethanol-free gas has a longer shelf life and does not degrade as quickly as ethanol-mixed fuels.


  • Availability: It can be more challenging to find, as not all gas stations carry ethanol-free gas.
  • Cost: Generally more expensive than regular gasoline, increasing the operating cost of lawn mowers.
  • Environmental Impact: Lacks the oxygenating benefits of ethanol, potentially contributing to more greenhouse gas emissions.

Frequently Asked Questions

Do fuel recommendations for small engines change at high altitudes?

Yes, at high altitudes, fuel requirements for small engines can change as the reduced air pressure can affect the fuel-air mixture. Manufacturers often recommend adjusting the carburetor and using higher octane fuel to prevent performance issues at elevated heights.

Can I use regular gas for my lawn mower?

Yes, regular gas, typically with an octane rating of 87 or higher, is suitable for most lawn mowers. However, it’s crucial to ensure the ethanol content is 10% or less and use fresh fuel to avoid engine damage or starting issues.

What is octane rating?

The octane rating of gasoline represents its ability to resist knocking or pinging during combustion. Higher octane ratings indicate greater knocking resistance, enabling smoother engine operation and preventing potential damage.

How to transport gas for a lawn mower?

When transporting gas for a lawn mower, use an approved fuel container, ensure it is sealed tightly to prevent spills and store it upright in a well-ventilated area of the vehicle. Avoid leaving the gas in the vehicle for an extended period, especially in hot weather, to minimize the risk of expansion and leakage.

How long does stored gasoline stay good?

Stored gasoline typically stays good for about three to six months. However, its shelf life can be extended to around a year with the addition of a fuel stabilizer. Over time, gasoline loses its volatility and oxidizes, leading to poor engine performance and starting problems.

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